破碎化生境中粗柄独尾草种群大小对繁殖特性的影响

景观破碎化是目前存在的一种普遍现象,导致物种生存的原有生境总面积减小,产生许多大小不一的斑块种群。不同斑块生境中植物种群的大小直接反映植物对环境的响应特征和适应对策,与植物繁殖有关的开花结实特性、种子形态及萌发特性的研究将有助于深入了解植物在不同生境中的生存策略。以粗柄独尾草(Eremurus inderiensis)为研究对象,以野外调查为基础,对比研究不同斑块粗柄独尾草种群的种群大小和生殖成功,揭示不同生境中粗柄独尾草的生态适应性。结果表明:(1)不同斑块生境中,种群大小差异较大,且较小的种群幼苗比例也较小,种群大小与种群幼苗比例呈显著相关;(2)较小的种群自然座果率、结籽率较低,种群间差异显著;(3)随着生境破碎化程度增加,种子千粒重,种子长、宽等形态特征呈减小趋势,但种翅占比增大;(4)在粗柄独尾草最适萌发温度下,随着生境破碎化程度增加,种子萌发率有下降趋势。针对人类干扰程度强的衰退型粗柄独尾草种群,亟需减少人为干扰,依据不同生境中的干扰因素及种群生存现状,制定科学与切实可行的保护和恢复策略。

The effect of population size on reproductive traits of Eremurus inderiensis in fragmented habitats

Landscape fragmentation, a widespread phenomenon, is considered a process by which the landscape not only breaks up and disjoints, but also changes from simple to complex status owing to disturbance by anthropogenic or other factors. Eremurus inderiensis (Liliaceae) is a perennial ephemeral geophyte herb. In China, E. inderiensis grows on fixed and semi-fixed sand dunes of the Gurbantunggut Desert in the Xinjiang Uyghur Autonomous Region. This kind of ephemeral plant contributes greatly to the stabilization of sand. Nowadays, increasing human activities have fragmented the original habitats of E. inderiensis populations in the southern Gurbantunggut Desert, resulting in numerous separate population patches. The sizes of plant populations in different patchy habitats directly reflect plant response characteristics and adaptation strategies to the environment. The study of plant flowering and fruiting characteristics and seed morphology and germination characteristics will help to understand plant survival strategy and evolutionary trends in different habitats. In this paper, we used E. inderiensis as the research object. Based on field investigation, we studied the population size and reproductive traits of this plant to reveal ecological adaptability of E. inderiensis in different patchy populations. Our results showed that there were significant differences in the population size and seedling proportion in different patches. Less fragmented patches had larger population sizes; the proportion of seedlings high in large populations and low in small populations. Small populations had lower flower number, fruit number, seed number, natural fruiting rate, and seed setting rate, with significant differences among populations. With the increase of habitat fragmentation, 1000-seed weight, seed length, and seed width showed a decreasing trend, while the proportion of seed wing showed an increasing trend. Seeds began to germinate after 20-30 days. The patch populations with different fragmentation degrees had different germination trends, and the maximum germination rate was achieved in about 40-50 days. Seed germination rate showed a decreasing trend with increasing habitat fragmentation. Further studies are needed to examine the effects of different combinations of disturbance factors on E. Inderiensis population status in different habitats to formulate scientific and practical protection and recovery strategies for this plant.